Telephone connection between exchanges of the decimal step-by-step type and the nondecimal revertive impulse control type



Apnl 19, 1949. J w. MCCLEW 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 17 Sheets-Sheet 1 2RG51 RFS D 2RGS2 Rl's RE T SLF was I s oRs 5E soooo- 89999 INVENTOR JOHN WILLIAM m: CLEW OWEN AVIS PEARCE ATTOR NEY Aprll 19, 1949. J, w. McCLEW ETAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REvERTIvE- IMPULSE coNTRoL TYPE Filed March 24, 1945 17 Sheets-Sheet 2 INYENTORS JOHN WILLIAM M CLEW OWEN AVIS PEARCE ATTORNEY J. w. MCCLEW EI'AL 2,467,490

17 Sheets-Shet 5 INVENTORS JOHN WILLIAM M CLEW OWEN AVIS PEARCE Q I NTORNEY April 19; 1949.

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 Aprll 19, 1949. J, w,' c w ETAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL S'TEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 1'7 Sheets-Sheet 4 INVENTORS JOHN WILLIAM Mq CLEW OWEN AVIS PEARCE ATTORNEY Aprl] 19, 1949. J, w, MccLEW ETAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 17 Sheets-Sheet 5 Lia INVENTOR 8 JOHN WILLIAM M CLEW OWEN AVIS PEARCE ATTORN EY April 19, 1949. J w. MECLEW ETAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 17 Sheets-Sheet 6 SSMC INVENTORS JOHN WILLIAM M CLEW OWEN AVIS PEARCE ZZZ ATTORNEY J. W. M CLEW ETAL TELEPHONE CONNECTIO DECIMAL STEP April 19, 1949. 2,467,490

N BETWEEN EXCHANGES OF THE 7 -BYSTEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 19,45

17 Sheets-Sheet '7 m n O W N T E R N L O E CE T V T N 00 A I. MM E M A US LV w IE ww JO Aprnl 19, 1949. J, CC E HAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 2 4, 1945 17 Sheets-Sheet 8 INVENTORS JOHN WILLIAM M CLEW OWEN AVIS PEARCE 25 I BY 2 ATTORNEY- Aprn] 19, 1949. J. w. MccLEw ETAL 1 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 P 17 Sheets-Sheet 9 N TH CDP I RSP ilMMc TMC A BY MD AYDEJ? (5Y4 Y" N w mz 8 9 v INVENTORS 7 JOHN WILLIAM MC CLEW OWEN AVIS PEARCE ATTORNEY April 19, 1949. J. w. McCLEW ETAL TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE 17 Sheets-Sheet 10 Filed March 24, 1945 BB5? vFl INVENTORS JOHN WILLIAM M GLEW OWEN AVIS PEARCE ATTORNEY Apr]! 19, 1949.

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDEGIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 19.45' 1'7 Sheets-Sheet 11 INVENTORS JOHN WILLIAM M CLEW OWEN AVIS PEARCE BYJ ATTORNEY J. w. MOCLEW ETAL 7,4 0

April 19, 1949. w, MCCLEW ETAL 2,467,490

' TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL I REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 17 Sheets-Sheet l2 6670M INVENTORS JOHN WILLIAM MC CLEW owsu AVIS PEARCE ATTO R NEY April 19, 194 J. w. M cLEw ETAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 1'7 Sheets-Sheet l3 INVENTORS JOHN WILLIAM M CLEW OWEN AVIS PEARCE ATTORNEY Aprnl 19, 1949.. J. w. McCLEW ETAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES. OF THE DECIMAL S-TEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE I Filed March 24, 1945 17 Sheets-Sheet 14 INVENTORS JOHN WILLIAM M cLEw OWEN AVIS PEARCE ATTORNEY Aprnl 19, 1949. J. w. McCLEW ETAL 2,467,490 TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE I DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24, 1945 1'7 Sheets-Sheet l5 INVENTORS JOHN WILLIAM M OLEW OWEN AVIS PEARCE ATTORN EY Apn] '19, 1949. J. w. M CLEW ETAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE Filed March 24;, 1945 17 Sheets-Sheet l6 UMC DMC cMc MMc 25 1 25 v 25 1 2s 1 556 u D2 62 M2 P P 5B4 5B7 5B8 INVENTORS v JOHN WILLIAM M OLEW OWEN AVIS PEARCE ATTORNEY April 19, 1949. J w MccLEW ETAL 2,467,490

TELEPHONE CONNECTION BETWEEN EXCHANGES OF THE DECIMAL STEP-BY-STEP TYPE AND THE NONDECIMAL REVERTIVE IMPULSE CONTROL TYPE 17 Sheets-Sheet. 17

Filed March 24, 1.945

PCOI

INVENTORS OHN WILLIAM M GLEW J v OWEN AVIS PEARCE ATTORNEY Patented Apr. 19, 1949 TELEPHONE CONNECTION BETWEEN EX- CHANGES OF THE DECIMAL STEP-BY- STEP TYPE AND THE NONDECIMAL RE- VERTIVE IMPULSE CONTROL TYPE John William McClew and Owen Avis Pearce, Liverpool, England, assignors to Automatic Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application March 24, 1945, Serial No. 584,510 In Great Britain April 1, 1944 12 Claims.

The present invention relates to telephone systems and in particular to systems including one 'or more exchanges employing switches operating on a direct setting decimal basis and one or more exchanges employing switches operating on a revertive control non-decimal basis. It has for its general object to provide interworking arrangements which will function to couple the above two types of exchange without necessitating alteration to the apparatus of either kind.

According to one feature of the invention, interworking between exchanges of the two types is catered for by the provision at the non-decimal exchange of equipment adapted to co-operate with switch-controlling registers thereat to transmit impulses on a decimal basis to the decimal exchange and of further equipment adapted to respond to impulses on a decimal basis transmitted from the decimal exchange and to control the setting of the revertively controlled switches in accordance therewith.

According to another feature of the invention in a telephone system including an exchange employing switches operating on a direct setting demical basis and an exchange employing switches operating on a revertive control nondecimal basis, equipment located at the nondecimal exchange for co-operating with switchcontrolling registers thereat includes an impulse storage and regenerating device for transmitting impulses on a decimal basis for operating the switches in the decimal exchange.

According to a further feature of the invention, in a telephone system including an exchange employing switches operating on a direct setting decimal basis and an exchange employing switches operating on a revertive control non-decimal basis, equipment located at the nondecimal exchange for responding to impulses on a decimal basis from the decimal exchange includes an impulse storage and regenerating device adapted to respond to impulses transmitted over a junction from the decimal exchange during the time that a non-numerical switch which is set in operation when the junction is seized is hunting for an idle set of registering equipment which is available in common to a group of incoming junctions.

The invention will be better understood from the following description'of one method of carrying it into effect, reference being had to the accompanying drawings comprising Figs. 1-19.

Of these, Fig. 1 shows a trunking diagram of two interlinked exchanges RE and SE in a net- Work, RE being an existing 10,000 line exchange of the non-decimal revertive impulse control Ericsson type using 500-point power drive selectors throughout and SE being a 10,000 line exchange of the decimal direct-setting Strowger type which it is desired to interwork with the. revertive exchange and which is assumed to employ IOU-point selectors throughout.

Fig. 2 shows the basis of the numbering arrangements assumed to be employed in the revertive exchange RE for the various group and final selector ranks which will be required.

Fig. 3 shows the circuit of an outgoing revertive to step-by-step relay set at exchange RE together with its associated converter hunter uniselector switch.

Figs. 4-9, when arranged in the manner shown in Fig. 10 which is located at the foot of Fig. 9-, show the circuit of a revertive to step-by-step converter at exchange RE.

Figs. 11 and 12 when arranged side by side with Fig. 11 on the left show the circuit of an outgoing step-by-step to revertive relay set at exchange SE.

Figs. 13 and 14 when arranged side by side with Fig. 13 on the left show the circuit of an incoming step-by-step to revertive" relay set at exchange RE together with its associated translator hunter switch.

Figs. 15-18 when arranged in the manner shown in Fig. 19 which is located at the foot of Fig. 18, show the circuit of a "step-by-step to revertive translator at exchange RE.

The revertive exchange RE is assumed to form part of a five-digit linked numbering scheme within which the step-by-step exchange SE has to operate, and assuming that the subscribers numbers 90,000-99,999 are allocated to exchange RE and that the 80,000 group is not already used in the linked numbering scheme, the numbers 80,00089.999 can be allocated to the exchange SE.

Referring firstly to Fig. 2, in the exchange RE there are twenty groups of 500 lines each, the groups being numbered 90,000-90,499, 90,500-90,999 99,500-99,999. Each selector has twenty-five multiple frames or levels of twenty outlets each, the levels being selected by a rotary motion and an outlet in a level being selected by a radial motion. First and second group selector ranks are provided, IRGS and 2RGSI being respective examples of such selectors. The various'levels of the first selectors may give access to outlets to twentyfive different 10,000 line exchanges, a particular level 8 giving access to the exchange RE second selectorrank. Twenty levels are utilised on .the

ranks of final selectors are provided and serve the nineteen subscribers groups 90,500-90,999,

. 99,500-99,999, access thereto being provided over levels 2-20 respectively ofthe second group" selectors.

The rotary movement of all selectors; which may involve up to 25 steps; is directed by what is usually termed a registenwhile" radial move-- ment along any selected level'fwhich mayinvolve up to 20 steps, is automatic in the case of group selectors and is directed by the register in: the case of final selectors. The direction of the selector by the register is performed by means of revertive impulses sent back by the selector to the register and corresponding in number to the number of steps the selector moves. Thereceptionof these revertive impulses in the controlling part of the register enables the register to stop the selector movement after'the requisite number of steps has been made in accordance with the number dialled. r The number of steps made by the selectors is relatedto the number dialled in the following manner. If the number 90499 is dialled into the register, it will be seen from Fig. 2 that the register will need to direct the first group selector IRJGS to level 8 in response to the first digit 9, the second group selector ZRGSI to level I in response to the second and third digits 04, the final selector RFS to level 25 inresponse to the third "and fourth digits 49 and then over this level to position 20 in response t'othe last two di its-99" Access to any one of the 10,000 subscribers is thus had overthree'ranks of selectors. The above remarks may be summarised as follows:

Dialled decimal digits, 904-9-9 Revertive non-decimaldigits, 8'1'25--20 Referring now to Fig. 1, each of the twenty groups of- 500 subscribers on the exchange RE is served by" a rank of 500-point line finder switches adapted to perform a rotary searchof up to 25 steps for a calling level followed by a radial search of up to 20 steps for a calling line" in that level.

If'subscriber RSI originates a call, he will be connected over line finder RLF and associated register hunter switch RH to the register R and will then receive dial tone. The receiving and registering part of the register then receives the digits dialled, say 90499, for a local call and the controlling part of theregister directs the setting of the first and second group selectors IRGS and 2RGS| and the final selector RFS to connect with the called party RS2 having the number 90499, the variousselectors being positioned as describedin connection with Fig. 2. Inthe exchange E the numbering follows a straightforward decimal basis. If a subscriber SSI originates a call, he will be connected over line finder SLF' or over an individual hunter switch to a first group selector [8018' and will then receive dial tone. Assuming that the required'subscriber SS2 has the number 80499, the first digit 8 will'be effective on the first group selector ISGS to raise its wipers vertically to level 8 after which hunting takes place in a rotary direction over the ten outlets to the rank or second group selectors-which give-access to ten-groups of 100 lines eaclron the-exchange.

Assuming second group selector 2SGSI is taken into use, the second digit dialled which is 0 will cause its wipers to be raised to the tenth level after which it will perform arotary search for one of a rank of third selectors serving the 1000 line group in which the called party is situated. The third digit dialled is effective on a group selector such as-SSGS to select the particular 100- line groupan'd' a final selector such as SFS then selects the particular subscriber SS2 in that group 'in' response to the dialling of the last two digits 99.

Considering now the interlinking arrangements between thejtwo' exchanges, junctions from exchange SE to exchange RE are taken from level 9 of the first selectors. Assuming subscriber SSI wishes to gain access to subscriber RS2 having the number 90499, the dialling of the first digit 9 will gain access to an outgoing junction relay set such as SORS, the other end of the junction being-terminated on the incoming relay set'RIRS whichhas associated therewith an incoming second group selector 2RGS2 and also a hunter switch TH. It will be understood that the incoming selectors suchas ZRGSZ are added in ex change RE when arrangements are made for interw'orkingwith exchange SE. 0n the seizure of the relay set RIRS, the hunter switch TH connectsit with a free translator T, the function or which is similar to that of the register R in that it has to direct the positioning of a non-decimal selector train-in response to dialled decimal digits. The remaining four dialled digits of the required number are repeated by relay set SORS through to the incoming relay set RIRS. In the 40 so that if the impulses are received before a free translator has been found, the digits can be stored. As soon as a free translator is found. the regenerator sends out the stored trains of impulses through to the translator. As fully described in the specification referred to, the regenerator' comprises essentially a receiving arm and a. sending or transmitting arm which are carried onopposite sides of a platecarrying a circular row of pins. The receiving arm is rotated step-by-step" in response to'incoming impulses and carries with it a marking lever which is released at the-end of each train of received impulses and which thereupon pushes a pin corresponding to' the digit dialled through the pin plate into the p'athof the sending arm. For each digit received a corresponding pin is pushed through the plate and these pins serveto determine'the movement of the sending arm which controlsthe generation of outgoing impulses.

When thetranslator has received the first two of the four decimal digits, it causes the second group selector ZRGSZto commence to operate to pick out a free finalselector in the appropriate 500-line" group. Thetranslator controls the settingof the second group selector 2RGS2 and final selector RFS by breaking the drive circuits of theseselectors when-the correct number-of revertive impulses have been received therefrom, this being done in the same general manner as is done by the registerR'but in this instance by the use" of standard relays 'and uniselectors. When the selectors have been positioned, the translator is released and becomes available for another call. The ringing of the called party's belliaeffectedi from the final selector RES and on the reply of the called party, this selector provides a transmission feed and at the same time returns a signal over the test wire of the connection to the incoming relay set RIRS which as in usual decimal system practice returns a reverse battery answering signal back over the junction line to exchange SE to brin about operation of the calling subscribers meter by means of positive battery potential applied back over the test lead P from the outgoing relay set SORS.

Assuming now that subscriber RS! wishes to connect with subscriber SS2 having the number 80499, the full five digits will be dialled into the register R. From Fig. 2 it will be seen that multiple frame or level 7 of the first selector banks is occupied by trunks leading to the ten thousand numbers of the exchange SE, and the selector is therefore directed to this level and then searches over the level to find a free outgoing relay set such as RORS, Fig. 1. On the seizure of the relay set RORS, the associated hunter switch CH connects with a free converter C. The converter sends back revertive impulse trains which are counted and interrupted by the register R as though the call were being completely set up on revertive selectors, and then sends forward to the decimal selectors of exchange SE corresponding decimal impulse trains which operate the second, third and final selectors at this exchange to route the call to the wanted party SS2. The register and converter are then released and become available for other calls. Ringing and transmission feed to the called subscriber are provided by the exchange SE final selector SFS which also transmits back an answering signal to the revertive exchange, the signal being received on relay set RORS which on the subsequent release of the connection, initiates the transmission of a metering signal back over the revertive exchange connection to meter the call against the calling party.

It will be appreciated that a number of stepbyestep and revertive exchanges could be interlinked together in similar manner, it being only necessary to allocate appropriate selector levels at the various exchanges for the interconnecting junction lines.

Considering now the detailed operation of the various interworking circuits and referring firstly to Fig. 3 which shows the circuit of an outgoing relay set such as RORS, Fig. 1, this is taken into use by the application of earth to the test wire from the first group selector IRGS in response to the dialling of a first digit 8. Relay JT operates and at contacts JIl completes a self-interrupted driving circuit via the magnet interrupter contacts CHMC for the magnet CHM of the converter hunter uniselector CH so that the wipers CHI-CH6 are rotated from the position they are already occupying in seach of a free converter which will be marked by resistance battery potential over an SW lead extending to bank CH3. When one is found, relay K rapidly opcrates over its two windings in series and thereupon at contacts Kl extends a guard earth via its ZO-ohm winding on to the outlet seized while at contacts K3 it brings up relay KA. This thereupon switches the incoming leads a and b through over wipers and banks CHI and CH2 into the converter C, the outgoing junction negative and positive leads being also switched through to the converter via wipers and banks CH4 and CH5 and a circuit being prepared for relay SZ.

The converter subsequently proceeds to send out decimal trains of impulses over the junction to set up the step-by-step selector train in exchange SE, and when all trains have been sent out, relay S2 is operated via the SZ lead and bank and wiper CH6 and thereupon locks up and at contacts SZ4 opens the converter seizing circuit so as to release it for further common use, while at the same time it releases relays K and KA in turn to switch theincoming leads a and b through to the junction. Relay I operates when contacts SZI and SZ3 close in series with the line relay at the distant end of the junction and at its contacts II energises the polarising winding of shunt field relay D which is not operative in this condition. It will be seen that during the slow release of relay KA magnet CHM is reenergised so that when relay KA releases the switch CH will advance its Wipers to the next position so as to give cyclic allocation of converters.

When the called subscribed at exchange SE answers, called subscriber answer supervision is received from the final selector in the usual form of battery reversal over the junction, whereupon the shunt field relay D operates and repeats the signal to the revertive equipment by applying earth at its contacts DI to the incoming 0 lead, this earth serving to hold relay JT independently of the 0 lead.

Conversation now proceeds, the revertive exchange calling subscriber being supplied with battery feeding current from the line finder in usual manner while the called partys battery feed is supplied from the step-by-step exchange final selector.

At the end of conversation, if the calling party clears first, relay JT is held from contacts DI, while if the called party clears first relay JT is held over the 0 lead from the line finder. When bothparties release, relays JT and SZ release in turn and the outgoing relay set is freed for further use, while the junction holding loop is opened at contacts SZI and SZ3 to release the selector train at exchange SE. In accordance with the usual practice of the revertiveexchange, the line finder proceeds to meter the call against the calling subscriber.

Referring now to Figs. 4-9, the converter circuit shown which corresponds to C, Fig. 1, is adapted to revert three non-decimal digits to the register from which it is seized and to send out four corresponding decimal digits which may or may not be preceded by an additional prefix decimal digit according to the interworking arrangements concerned. In the present instance where the revertive exchange trunks into second group selectors at a five-digit step-by-step exchange, no prefix digit needs to be sent, and to secure this method of operation terminals I2 and I3, Fig. 6, are strapped.

The converter is taken into use over the SW lead from the converter hunter CH and thereupon relay T, Fig. 4, operates and brings up relay TA, Fig. 7, which opens the various homing circuits. The idle marking battery normally applied to the SW lead via the winding of relay T in parallel with the series-connected resistor AYB and magnet SSM, Fig. 5, extends via the home position of the' digit distributor DD and the unlselectors VG, VV and RV associated with revertive impulse sending so that after having been taken into use and set into operation the converter will remain guarded until all these uniselectors have been restored to normal.

As soon as the register R, Fig. 1, is ready to receive revertive impulses, relay SR, Fig. 4, is operated over the "b lead and bringsup relay PR, 

